Two key analog components in integrated circuit design are the operational amplifier (“op-amp”) and the type II current conveyor (“CCII”). FIG. 1(a) depicts an op-amp, which is a high-gain amplifier with two inputs and a single output. As shown, the op-amp has a positive input with a voltage VP and a current IP, a negative input with a voltage VN and a current IN, and an output with a voltage VOUT and a current IOUT. Ideally, the impedances of the inputs are very high, such that the input currents Ip and IN are zero. Further, the op-amp ideally operates as a differential amplifier that amplifies a difference between these two inputs by an open-loop gain AV, which is typically very large (e.g., AV>10,000). As such, the operation of the op-amp may be represented as VOUT=AV (VP−VN). In practice, most applications require an amplifier gain that is much less than the op-amp's open-loop gain AV. As such, the op-amp is typically configured with some form of feedback such that it performs a closed-loop operation. Within this configuration, the op-amp may output a value at VOUT to ensure that VP=VN. Therefore, the 20 operation of the op-amp may be defined by two approximations: (1) VP−VN=0 and (2) IP=IN=0. There may be various different implementations of the op-amp.
FIG. 11(b) depicts a CCII, which also has two inputs and a single output. As shown, the CCII may have a positive input Y with a voltage VP and a current IP, a negative input X with a voltage VN and a current IN, and an output Z with a voltage VOUT and a current IOUT. Ideally, the impedance of the negative input X is very low and the impedance of the positive terminal Y is very high. The operation of the CCII may then be defined by three approximations: (1) VN=VP, (2) IOUT=IN, and (3) IP=0. There may be various different implementations of the CCII.
While an integrated circuit designer may use the op-amp and/or the CCII to perform similar functions, op-amps and CCIIs each have respective benefits and drawbacks. In this respect, op-amps may be more appropriate for some applications, while CCIIs may be more appropriate for other applications. As such, an integrated circuit designer typically must weigh these benefits and drawbacks to decide which component to use for each new application. In turn, the integrated circuit designer's library must include both components. It would be desirable, however, to have a single analog component that functions as both an op-amp and a CCII.